The invention relates in general to movable barrier operators and in particular to movable barrier operators such as garage door operators or gate operators which include passive infrared detectors associated with them for detecting the presence of a person or other high temperature object for controlling a function of the movable barrier operator such as illumination.
It has been known to use pyroelectric infrared detectors or passive infrared (PIR) detectors for the detection of a person in a particular vicinity. For instance, it is well known that pyroelectric infrared detectors can be used in combination with illumination lamps, carriage lamps, spot lamps and the like to form a low cost home security system. The pyroelectric infrared detector typically has a plurality of segments. One or more of the segments may be actuated by infrared radiation focused thereon by a Fresnel lens positioned in front of the PIR detector. The pyroelectric detector provides an output signal when a change occurs in the potential level between one element and another element in the array. Such an infrared detected voltage change indicates that a warm object radiating infrared radiation, typically a person, is moving with respect to the detector. The detectors to provide output signals upon receiving infrared radiation in about the ten micron wavelength range. The micron infrared radiation is generated by a body having a temperature of about 90xc2x0 F., around the temperature of a human body (98.6xc2x0 F.).
It is also known that garage door operators or movable barrier operators can include a passive infrared detector associated with the head unit of the garage door operator. The passive infrared detector, however, needed some type of aiming or alignment mechanism associated with it so that it could be thermally responsive to at least part of the garage interior. The detectors were connected so that upon receiving infrared energy from a moving thermal source, they would cause a light associated with the garage door operator to be illuminated.
It was known in the past to use timers associated with such systems so that if there were no further thermal signal, the light would be shut off after a predetermined period. Such units were expensive as the passive infrared detector had to be built into the head unit of the garage door operator. Also, the prior PIR detectors were fragile. During mounting of the head unit to the ceiling of the garage a collision with the aiming device associated with the passive infrared detector might damage them. The ability to aim the detection reliably was deficient, sometimes leaving blank or dead spots in the infrared coverage.
Still other operators using pivoting head infrared detectors required that the detector be retrofitted into the middle of the output circuit of a conventional garage door operator. This would have to have been done by garage door operator service personnel as it would likely involve cutting traces on a printed circuit board or the like. Unauthorized alteration of the circuit board by a consumer might entail loss of warranty coverage of the garage door operator or even cause safety problems.
What is needed then is a passive infrared detector for controlling illumination from a garage door operator which could be quickly and easily retrofitted to existing garage door operators with a minimum of trouble and without voiding the warranty.
A passive infrared detector for a garage door operator includes a passive infrared detector section connected to a comparator for generating a signal when a moving thermal or infrared source signal is detected by the passive infrared detector. The signal is fed to a microcontroller. Both the infrared detector and the comparator and the microcontroller are contained in a wall control unit. The wall control unit has a plurality of switches which would normally be used to control the functioning of the garage door operator and are connected in conventional fashion thereto.
The PIR detector is included with the switches for opening the garage door, closing the garage door and causing a lamp to be illuminated. The microcontroller also is connected to an illumination detection circuit, which might typically comprise a cadmium sulphide (CdS) element which is responsive to visible light. The CdS element supplies an illumination signal to an ambient light comparator which in turn supplies an illuminator level signal to the microcontroller. The microcontroller also controls a setpoint signal fed to the comparator. The setpoint signal may be adjusted by the microcontroller according to the desired trip point for the ambient illumination level.
The microcontroller also communicates over the lines carrying the normal wall control switch signals with a microcontroller in a head unit of the garage door operator. The wall control microcontroller can interrogate the garage door operator head unit with a request for information. If the garage door operator head unit is a conventional unit, no reply will come back and the wall control microcontroller will assume that a conventional garage door operator head is being employed. In the event that a signal comes back in the form of a data frame which includes a flag that is related to whether the light has been commanded to turn on, the microcontroller can then respond and determine in regard to the status of the infrared detector and the ambient light whether the light should stay on or be turned off.
In the event that a conventional garage door operator head is used, the microcontroller can, in effect, create a feedback loop with the head unit by sending a light toggling signal to the microcontroller in the head unit commanding it to change the light state. If the light turns on, the increase in illumination is detected by the cadmium sulphide sensor and so signaled to the microcontroller head allowing the light to stay on. If, in the alternative, the light is turned off and the drop in light output is detected by the cadmium sulphide detector, the wall control microcontroller then retoggles the light, switching it back on to cause the light to stay on for a full time period allotted to it, usually two-and-one-half to four-and-one-half minutes.
It is a principal aspect of the present invention to provide a quickly and easily retrofitted passive infrared detector for controlling the illumination of a garage door operator through conventional signaling channels.
It is another aspect of the instant invention to provide a garage door operator having a passive infrared detector which passive_infrared detector_can control a variety of garage door operators.
Other aspects and advantages of the present invention will become obvious to one of ordinary skill in the art upon a perusal of the following specification and claims in light of the accompanying drawings.